The invention relates to a method for adjusting the workpiece flow in a production system, including workpieces and workpiece agents associated with the workpieces, machines for machining the workpieces, and machine agents associated with the machines and transportation means for transporting the workpieces between the machines and transportation agents associated with the transportation means.
Known methods for adjusting the workpiece flow in a production system are distinguished by the deposition in memory of the entire structure of the production system in the workpiece agent assigned to the workpiece. First, the workpiece agent of a workpiece reports to a machine agent for a machining variant and tasks a transportation agent to vary the transportation arrangement in such a way that the workpiece is assigned to a specified destination exit, so that the transportation to the desired machine can be carried out.
In this case, the global topography of the production system must be known in all the workpiece agents, since it is the workpiece agent that first informs the transportation agent as to which destination exit of a transportation means is to be established.
Upon a reconfiguration of the production system, especially in the event of local changes such as removing and/or adding machines, all the workpiece agents must be informed of this change, which entails major effort and expense.
With this as the point of departure, the object of the present invention is to refine a method of the type defined above, in such a way as to furnish as flexible as possible a production system, which is tolerant of at least partial failures of system components and thus has enhanced productivity.
This object is attained according to the invention in that each transportation agent is assigned at least one machine with a specified machine address Mn; the transportation agent is tasked to transport the workpiece to a desired destination machine address; and the transportation agent autonomously controls the transportation means in such a way that the workpiece is transported to the machine with the destination machine address via a specified destination exit.
By this provision of the invention, it is attained that the global topography of the entire production system does not have to be known in all the workpiece agents. Instead, a local assignment of a machine address to a transportation agent is made, and then only this machine address is assigned to that transportation agent. The workpiece agent thus tasks the transportation agent to make a connection with a desired destination machine address. The destination machine address obtained is compared with the local machine address, and as a function of the comparison, the workpiece is either shunted out, transported in the production direction or counter to the production direction, depending on whether the desired destination machine address is greater or less than the local machine address.
The method of the invention is distinguished in particular in that the production system can easily be modified, since local changes such as removing and/or adding machines need to be configured only locally. For instance, if one machine fails, this change need merely be informed to the local transportation agent, to which that machine had been assigned as a local machine address. If this machine address is requested by a workpiece agent, the transportation agent can decide on its own which alternative machine address the workpiece should be transported to.
Advantageously, the machines are disposed in series, and the machine addresses are assigned in increasing order in the production direction. To make later expansions easy, the machine addresses are allocated with gaps in them.
To assure the most flexible, congestion-free transport of the workpieces, these workpieces are transported in different directions over a plurality of transportation paths, and the workpieces are assigned to specified transportation paths as a function of control commands of the transportation agent, in order to reach the desired destination machine address.
The workpiece agent, transportation agent and machine agent are implemented as blocks or software programs in a memory-programmable controller or a personal computer. The performance or mode of operation of the transportation agent, workpiece agent and machine agent, is observed by means of higher-ranking monitoring agents. If one workpiece agent fails, the workpiece can for instance be automatically taken over by a further workpiece agent. The agents also communicate with one another and inform each other of their status at the time.
Further details, advantages and characteristics of the invention will become not only from the claims and the characteristics drawn from them xe2x80x94taken alone and/or in combination xe2x80x94but also from the ensuing description of a preferred exemplary embodiment shown in the drawing.